汽车活塞环表面Ni60A-Cr2O3复合涂层的制备与性能

Preparation and Properties of Ni60A-Cr2O3 Composite Coating on Surface of Automobile Piston Ring

采用超声速等离子喷涂法在汽车活塞环用45钢表面制备了Ni60A-Cr2O3复合涂层,通过X射线衍射(XRD),扫描电镜(SEM),摩擦磨损试验,电化学试验和浸泡腐蚀试验研究了Cr2O3含量对Ni60A-Cr2O3复合涂层物相组成、显微组织、耐磨性能和耐腐蚀性能的影响。结果表明:Ni60A-Cr2O3复合涂层中除有增强相Cr2O3外,还含有FeNi3、Fe(C,B)6和Cr23C6等含Cr析出相;随着复合涂层中Cr2O3含量的增加,复合涂层的磨损量呈现先减小而后增加的趋势,在Cr2O3质量分数为35%时磨损量最小,Ni60A-Cr2O3复合涂层中适宜的Cr2O3添加量为35%;Ni60A涂层和35%Cr2O3+65%Ni60A复合涂层的磨损机制分别为黏着磨损和磨粒磨损;极化曲线测试结果和浸泡腐蚀试验结果都表明,在1.5mol/L H2SO4和3.5%NaCl溶液中,35%Cr2O3+65%Ni60A复合涂层的耐腐蚀性能都要优于Ni60A涂层的。

The Ni60 A-Cr2O3 composite coatings were prepared on surface of 45 steel for automobile piston ring by hypersonic plasma spraying.The effects of Cr2O3 content on the phase composition,microstructure,wear resistance and corrosion resistance of the Ni60 A-Cr2O3 composite coatings were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),frication and wear testing,electrochemical testing and immersion corrosion testing.The results show that in addition to the enhanced phase Cr2O3,FeNi3,Fe(C,B)6,Cr23C6 and other Cr precipitates were formed in the Ni60 A-Cr2O3 composite coatings.With the increase of Cr2O3 content in the composite coatings,the wear-loss of the composite coatings decreased first and then increased,and the minimum value of the wear-loss was obtained when the Cr2O3 mass fraction was 35%,and the suitable amount of Cr2O3 added to the Ni60 A-Cr2O3 composite coatings was 35%.The wear mechanism of the Ni60 A coating and the 35% Cr2O3+65%Ni60 A composite coating were adhesive wear and abrasive wear,respectively.The test results of polarization curves and immersion corrosion test showed that the corrosion resistance of 35% Cr2O3+65%Ni60 Acomposite was better than that of the Ni60 Acoating both in 1.5 mol/L H2 SO4 solution and in 3.5% NaCl solution.